1. Field of the Invention
The present invention relates to an engine cooling system, and more particularly to an engine cooling system including a cross-flow or tangential fan or fans driven by a motor for cooling an engine on an automotive vehicle.
2. Description of the Prior Art
FIG. 1 of the accompanying drawings illustrates an engine cooling system for use in an automotive vehicle having an engine 2 disposed in a front nose portion 1. The engine cooling system includes a cross-flow or tangential fan 4 driven through an endless belt 3 by the engine 2 to rotate in the direction of the arrow a. A radiator 5 is disposed at the front end of the nose portion 1 in front of the cross-flow fan 4 and subjected to an air flow in the direction of the arrow b while the vehicle is running. Upper and lower casings 6, 7 extend rearward from the upper and lower ends, respectively, of the radiator 5 in partly covering relation to the cross-flow fan 4 for guiding the air flow from the radiator 5 to the cross-flow fan 4. Designated at W is a front wheel of the vehicle.
The cross-flow fan 4 has a shaft 4a supported by the casing 6 or 7 (that is, a body member of the vehicle), and the shaft 4a is operatively coupled by the endless belt 3 to the engine 2. Therefore, the fan shaft 4a is subjected to vibrations of the engine 2 and also vibrations of the vehicle body when the vehicle travels. Since the casings 6, 7 undergo vibrations of the vehicle body only, the casings 6, 7 and the fan 4 move relatively to each other. The casings 6, 7 and the fan 4 are spaced from each other with as small a distance therebetween as possible to increase the speed of travel of the air flow and keep a desired rate of air flow for higher engine cooling efficiency. This however has led to a problem in that the the casings 6, 7 tend to contact the fan 4 when they are relatively moved, thus damaging the fan 4. If the casings 4, 7 were spaced widely from the fan 4 in order to prevent the latter from being damaged, no desired rate of air flow could be achieved and the engine cooling efficiency could not be increased.
The cross-flow fan 4 is also partly covered by lateral casings (not shown in FIG. 1) to avoid any unwanted reduction in the efficiency of the fan while the vehicle is being driven at medium and high speeds. When the vehicle is idling or running at low speeds, however, the casings covering the fan are liable to obstruct an air flow directed to the fan, with the result that no sufficient rate of air flow cannot be assured and the engine cooling efficiency is lowered.
Various arrangements have been known for increasing the rate of air flow through the radiator to thereby cool the coolant for cooling the engine. For example, the cross-flow fan has an increased outside diameter and a larger axial length. This attempt is disadvantageous in that a large installation space in longitudinal and transverse directions should be provided in a small engine compartent for accommodating such a cross-flow fan. However, in reality, no sufficient installation space cannot be obtained in the longitidinal and transverse directions, though a small vertical space is available in the engine compartment. Another effort has been to increase the RPM of the cross-flow fan during operation. This arrangement has a drawback in that the cross-flow fan is subjected to an undue load and rendered less durable since a cross-flow fan of a capacity large enough to withstand the desired high RPM cannot be installed in actual applications.